Add support for system messages not updating channel.lastMessageAt

CHANGELOG.md

@@ -4,6 +4,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 # Upcoming
 
 ## StreamChat
+### ✅ Added
+- Add support for system messages not updating `channel.lastMessageAt` [#3476](https://github.com/GetStream/stream-chat-swift/pull/3476)
 ### 🐞 Fixed
 - Fix watching channels when performing channel search [#3472](https://github.com/GetStream/stream-chat-swift/pull/3472)
 

DemoApp/StreamChat/Components/DemoChatChannelListRouter.swift

@@ -408,10 +408,8 @@ final class DemoChatChannelListRouter: ChatChannelListRouter {
                 }
             }),
             .init(title: "Show Channel Info", handler: { [unowned self] _ in
-                self.rootViewController.presentAlert(
-                    title: "Channel Info",
-                    message: channelController.channel.debugDescription
-                )
+                let debugViewController = DebugObjectViewController(object: channelController.channel)
+                self.rootViewController.present(debugViewController, animated: true)
             }),
             .init(title: "Show Channel Members", handler: { [unowned self] _ in
                 guard let cid = channelController.channel?.cid else { return }

Sources/StreamChat/APIClient/Endpoints/Payloads/ChannelListPayload.swift

@@ -224,6 +224,7 @@ public class ChannelConfig: Codable {
         case commands
         case createdAt = "created_at"
         case updatedAt = "updated_at"
+        case skipLastMsgAtUpdateForSystemMsg = "skip_last_msg_update_for_system_msgs"
     }
 
     /// If users are allowed to add reactions to messages. Enabled by default.
@@ -258,6 +259,8 @@ public class ChannelConfig: Codable {
     public let updatedAt: Date
     /// Determines if polls are enabled.
     public let pollsEnabled: Bool
+    /// Determines if system messages should not update the last message at date.
+    public let skipLastMsgAtUpdateForSystemMsg: Bool
 
     public required init(from decoder: Decoder) throws {
         let container = try decoder.container(keyedBy: CodingKeys.self)
@@ -282,6 +285,7 @@ public class ChannelConfig: Codable {
         createdAt = try container.decode(Date.self, forKey: .createdAt)
         updatedAt = try container.decode(Date.self, forKey: .updatedAt)
         pollsEnabled = try container.decodeIfPresent(Bool.self, forKey: .pollsEnabled) ?? false
+        skipLastMsgAtUpdateForSystemMsg = try container.decodeIfPresent(Bool.self, forKey: .skipLastMsgAtUpdateForSystemMsg) ?? false
     }
 
     internal required init(
@@ -296,6 +300,7 @@ public class ChannelConfig: Codable {
         mutesEnabled: Bool = false,
         pollsEnabled: Bool = false,
         urlEnrichmentEnabled: Bool = false,
+        skipLastMsgAtUpdateForSystemMsg: Bool = false,
         messageRetention: String = "",
         maxMessageLength: Int = 0,
         commands: [Command] = [],
@@ -318,5 +323,6 @@ public class ChannelConfig: Codable {
         self.createdAt = createdAt
         self.updatedAt = updatedAt
         self.pollsEnabled = pollsEnabled
+        self.skipLastMsgAtUpdateForSystemMsg = skipLastMsgAtUpdateForSystemMsg
     }
 }

Sources/StreamChat/Database/DTOs/ChannelConfigDTO.swift

@@ -11,6 +11,7 @@ final class ChannelConfigDTO: NSManagedObject {
     @NSManaged var typingEventsEnabled: Bool
     @NSManaged var readEventsEnabled: Bool
     @NSManaged var connectEventsEnabled: Bool
+    @NSManaged var skipLastMsgAtUpdateForSystemMsg: Bool
     @NSManaged var uploadsEnabled: Bool
     @NSManaged var repliesEnabled: Bool
     @NSManaged var quotesEnabled: Bool
@@ -37,6 +38,7 @@ final class ChannelConfigDTO: NSManagedObject {
             mutesEnabled: mutesEnabled,
             pollsEnabled: pollsEnabled,
             urlEnrichmentEnabled: urlEnrichmentEnabled,
+            skipLastMsgAtUpdateForSystemMsg: skipLastMsgAtUpdateForSystemMsg,
             messageRetention: messageRetention,
             maxMessageLength: Int(maxMessageLength),
             commands: Array(Set(
@@ -76,6 +78,7 @@ extension ChannelConfig {
         dto.updatedAt = updatedAt.bridgeDate
         dto.commands = NSOrderedSet(array: commands.map { $0.asDTO(context: context) })
         dto.pollsEnabled = pollsEnabled
+        dto.skipLastMsgAtUpdateForSystemMsg = skipLastMsgAtUpdateForSystemMsg
         return dto
     }
 }

Sources/StreamChat/Database/DTOs/MessageDTO.swift

@@ -813,7 +813,11 @@ extension NSManagedObjectContext: MessageDatabaseSession {
             array: payload.threadParticipants.map { try saveUser(payload: $0) }
         )
 
-        channelDTO.lastMessageAt = max(channelDTO.lastMessageAt?.bridgeDate ?? payload.createdAt, payload.createdAt).bridgeDate
+        let isSystemMessage = dto.type == MessageType.system.rawValue
+        let shouldNotUpdateLastMessageAt = isSystemMessage && channelDTO.config.skipLastMsgAtUpdateForSystemMsg
+        if !shouldNotUpdateLastMessageAt {
+            channelDTO.lastMessageAt = max(channelDTO.lastMessageAt?.bridgeDate ?? payload.createdAt, payload.createdAt).bridgeDate
+        }
 
         dto.channel = channelDTO
 

Sources/StreamChat/Database/StreamChatModel.xcdatamodeld/StreamChatModel.xcdatamodel/contents

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="UTF-8" standalone="yes"?>
-<model type="com.apple.IDECoreDataModeler.DataModel" documentVersion="1.0" lastSavedToolsVersion="23231" systemVersion="24A348" minimumToolsVersion="Automatic" sourceLanguage="Swift" userDefinedModelVersionIdentifier="">
+<model type="com.apple.IDECoreDataModeler.DataModel" documentVersion="1.0" lastSavedToolsVersion="22758" systemVersion="23G93" minimumToolsVersion="Automatic" sourceLanguage="Swift" userDefinedModelVersionIdentifier="">
     <entity name="AttachmentDTO" representedClassName="AttachmentDTO" syncable="YES">
         <attribute name="data" attributeType="Binary"/>
         <attribute name="id" attributeType="String"/>
@@ -28,6 +28,7 @@
         <attribute name="readEventsEnabled" attributeType="Boolean" defaultValueString="NO" usesScalarValueType="YES"/>
         <attribute name="repliesEnabled" attributeType="Boolean" defaultValueString="NO" usesScalarValueType="YES"/>
         <attribute name="searchEnabled" attributeType="Boolean" defaultValueString="NO" usesScalarValueType="YES"/>
+        <attribute name="skipLastMsgAtUpdateForSystemMsg" attributeType="Boolean" defaultValueString="NO" usesScalarValueType="YES"/>
         <attribute name="typingEventsEnabled" attributeType="Boolean" defaultValueString="NO" usesScalarValueType="YES"/>
         <attribute name="updatedAt" attributeType="Date" usesScalarValueType="NO"/>
         <attribute name="uploadsEnabled" attributeType="Boolean" defaultValueString="NO" usesScalarValueType="YES"/>

TestTools/StreamChatTestTools/Fixtures/JSONs/Channel.json

@@ -1318,6 +1318,7 @@
       "created_at" : "2019-03-21T15:49:15.40182Z",
       "automod" : "AI",
       "read_events" : true,
+      "skip_last_msg_update_for_system_msgs": true,
       "commands" : [
         {
           "set" : "fun_set",

TestTools/StreamChatTestTools/Mocks/Models + Extensions/ChatChannel_Mock.swift

@@ -18,6 +18,7 @@ public extension ChannelConfig {
         searchEnabled: Bool = true,
         mutesEnabled: Bool = true,
         urlEnrichmentEnabled: Bool = true,
+        skipLastMsgAtUpdateForSystemMsg: Bool = false,
         messageRetention: String = "",
         maxMessageLength: Int = 0,
         commands: [Command] = [Command(name: "Giphy", description: "", set: "", args: "")],
@@ -35,6 +36,7 @@ public extension ChannelConfig {
             searchEnabled: searchEnabled,
             mutesEnabled: mutesEnabled,
             urlEnrichmentEnabled: urlEnrichmentEnabled,
+            skipLastMsgAtUpdateForSystemMsg: skipLastMsgAtUpdateForSystemMsg,
             messageRetention: messageRetention,
             maxMessageLength: maxMessageLength,
             commands: commands,

Tests/StreamChatTests/APIClient/Endpoints/Payloads/ChannelListPayload_Tests.swift

@@ -328,6 +328,7 @@ final class ChannelPayload_Tests: XCTestCase {
         XCTAssertEqual(config.urlEnrichmentEnabled, true)
         XCTAssertEqual(config.messageRetention, "infinite")
         XCTAssertEqual(config.maxMessageLength, 5000)
+        XCTAssertEqual(config.skipLastMsgAtUpdateForSystemMsg, true)
         XCTAssertEqual(
             config.commands,
             [.init(name: "giphy", description: "Post a random gif to the channel", set: "fun_set", args: "[text]")]

Tests/StreamChatTests/Database/DTOs/MessageDTO_Tests.swift

@@ -1960,6 +1960,52 @@ final class MessageDTO_Tests: XCTestCase {
         XCTAssertEqual(channel.lastMessageAt?.bridgeDate, newerMessagePayload.createdAt)
     }
 
+    func test_messageDoesNotUpdateChannelsLastMessageAt_whenSystemMessageAndSkipIsEnabled() throws {
+        let userId: UserId = .unique
+        let messageId: MessageId = .unique
+        let channelId: ChannelId = .unique
+        // Save channel with some messages
+        let channelPayload: ChannelPayload = dummyPayload(
+            with: channelId,
+            numberOfMessages: 5,
+            channelConfig: .mock(skipLastMsgAtUpdateForSystemMsg: true)
+        )
+        let originalLastMessageAt: Date = channelPayload.channel.lastMessageAt ?? channelPayload.channel.createdAt
+        try database.writeSynchronously {
+            try $0.saveChannel(payload: channelPayload)
+        }
+
+        // Create a new message payload that's older than `channel.lastMessageAt`
+        let olderMessagePayload: MessagePayload = .dummy(
+            messageId: messageId,
+            authorUserId: userId,
+            createdAt: .unique(before: channelPayload.channel.lastMessageAt!)
+        )
+        assert(olderMessagePayload.createdAt < channelPayload.channel.lastMessageAt!)
+        // Save the message payload and check `channel.lastMessageAt` is not updated by older message
+        try database.writeSynchronously {
+            try $0.saveMessage(payload: olderMessagePayload, for: channelId, syncOwnReactions: true, cache: nil)
+        }
+        var channel = try XCTUnwrap(database.viewContext.channel(cid: channelId))
+        XCTAssertNearlySameDate(channel.lastMessageAt?.bridgeDate, originalLastMessageAt)
+
+        // Create a new message payload that's newer than `channel.lastMessageAt`
+        let newerMessagePayload: MessagePayload = .dummy(
+            type: .system,
+            messageId: messageId,
+            authorUserId: userId,
+            createdAt: .unique(after: channelPayload.channel.lastMessageAt!)
+        )
+        assert(newerMessagePayload.createdAt > channelPayload.channel.lastMessageAt!)
+
+        // Save the message payload and check `channel.lastMessageAt` is not updated.
+        try database.writeSynchronously {
+            try $0.saveMessage(payload: newerMessagePayload, for: channelId, syncOwnReactions: true, cache: nil)
+        }
+        channel = try XCTUnwrap(database.viewContext.channel(cid: channelId))
+        XCTAssertNotEqual(channel.lastMessageAt?.bridgeDate, newerMessagePayload.createdAt)
+    }
+
     func test_saveMultipleMessagesWithSameQuotedMessage() throws {
         // We check whether a message can be quoted by multiple other messages in the same channel
         // Here, secondMessage and thirdMessage quote the firstMessage